A friend posted this on Facebook:

I think it's okay. It respects the original while adding a little something fresh. I wonder who the guy who plays "What" is. I felt bad when he didn't get big cheers like the others.

To be honest, for a long time I had found the original a little stale, but I think that's because I'd heard so many amateur reenactments. No offense to the amateurs — this routine was practically made to be repeated and enjoyed by all comers forever and ever — but I just watched a couple of Abbott and Costello's performances, and you can see the difference between mastering the lines and mastering the performance. It's all about the reactions. It's no use delivering the lines with rapid-fire precision if we don't see the cumulative effect on Costello's emotions, while Abbott in his own mind is giving exactly the perfectly reasonable answers Costello is asking. To get those reactions — and to keep the wording confusing enough for Costello but clear enough for the audience, without sounding scripted — that's the brilliance of this routine. I am sure it could only have been accomplished over thousands of rehearsals and hundreds of performances.

Here's one performance:

When I watched this video I noticed it didn't exactly match the script I've heard over and over. It turns out:

"Who's on First?" is believed to be available in as many as 20 versions, ranging from one minute to about 10 minutes. The team could time the routine at will, adding or deleting portions as needed for films, radio, or television.

That they could adjust bits of it on demand and keep up the speed and spontaneity is just another sign of their brilliance and virtuosity.